Interpreting XIRR for Irregular Trading Cash Flows
Summary
The document explains XIRR as the annualized rate that equates a dated series of irregular cash flows with an equivalent constant-rate investment. Its examples contrast a simple loan with interest paid at different dates and a short holding-period trade, illustrating that timing changes the annualized figure even when the underlying cash gain may seem similar. It also clarifies that idle capital is not automatically represented unless it appears in the cash-flow setup.
The discussion cautions that XIRR can be a poor standalone measure when investment intervals are short: annualizing a brief trade can make the reported rate sensitive to a small timing change. It suggests considering the money multiple alongside IRR, as some real estate transactions do. These interpretations rely on the simplifying assumption of a constant equivalent rate over the cash-flow period; the document does not specify a complete portfolio accounting method for strategy evaluation.
Key ideas
- XIRR annualizes a dated series of irregular cash flows as an equivalent constant rate.
- Cash-flow timing can change XIRR even when the total gain is unchanged.
- Annualized returns can be misleading for short holding periods because small timing differences affect the rate.
- Pairing IRR with a money multiple can give context about both return magnitude and duration.
- The calculation does not by itself resolve how to account for capital that remains idle.
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Full text
# What does XIRR show? # What does XIRR show? I've put aside 1000 EUR for trading strategy test. Made number of trades where each position was worth 5 EUR. At any moment there was invested from 0 to 80 EUR. Entered all cashflows to XIRR function and it shows 0,14. What does it mean? I suppose it means 14% return from some sum over some period. I assume the period is 1 year, but what is the sum that gives 14%? Should I somehow add funds that sit idle? For example I bought an asset on 1st of Jan for 5 EUR and in 3 days sold it with 0,2 EUR profit. Cashflows for this trade are: 2021-01-01; -5 2021-01-04; +5 2021-01-04; +0,2 ## Answer by demully (score 2, accepted) https://quant.stackexchange.com/a/60535 In its simplest form, for a series of irregular and/or intermittent cashflows that defy description in traditional terms (like bond coupons, dividends, etc.)... XIRR tells you "what interest rate would a bank have to offer to give me the same end result, given all the same cashflows at the same times?". The implicit and necessary assumption being a constant equivalent interest rate over the whole period. ## Answer by Pythonista anonymous (score 1) https://quant.stackexchange.com/a/66726 OP, I assume you have done a modicum of research on the concept of "internal rate of return"? If so, what, exactly, is not clear? Explaining what is not clear would be more helpful than asking for an explanation of a concept. ### Some examples XIRR calculates the internal rate of return for a set of irregular cashflows. There are plenty of resources on what this means, so I am not going to repeat the definition here. Say you invest 100 now, then you get 10 of interest after 1 year and 110 (principal + interest) after 2 years. Your IRR is 10%, and you can calculate it with Excel's IRR function. The easiest, non-mathematically rigorous interpretation is that this is the return you make if you lend 100 now, get 10 of interest after 1 year, then at Y2 you get 10 of interest and your principal back. Now imagine the same cashflows happen on: 1-May-2021, 1-Feb-2022, and 1-Dec-2022. The IRR will be 12.80% and you can calculate this with Excel's XIRR function. The interpretation is the same as above. ### A practice question for you Let's say I lend €1000 to you and €1000 to your brother. In both cases, principal to be repaid after 1 year, and 5% interest. However, you pay me interest every month, your brother only after a year. Do you think the IRRs will be the same? Yes / no / why? ### A clarification The IRR becomes a rather irrelevant metric when the time interval is small. Let's say you buy something for 100 on 1-Jan and sell it for 110 on 1-Apr. Your IRR is 47.19%. If instead you sell it one week later, the IRR drops to 43.14%. In many cases (think of a manufacturer or retailer selling its inventory) selling a week later is not the end of the world - what does such a drop in IRR mean? Well, practically not much! In these cases, looking at the money multiple may be more relevant. In fact, many real estate transactions are based on a combination of these two metrics. A counterparty gets paid more upon reaching certain targets of IRR and of money multiple. An example could be a real estate deal where your partner is tasked with selling the apartments you are building in a condo. A minimum money multiple ensures that a short timeframe doesn't distort the results, and a minimum high IRR ensures the opposite, ie that you don't pay too much for a high multiple obtained over too long a period. ## Answer by Luke Krause (score -1) https://quant.stackexchange.com/a/66703 The XIRR is simply returning an effective annual rate. So, in order to achieve the XIRR you have to assume that the money stays fully invested for the entire year.
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